treatment. Chairman - JPC . CCP

Onchocerciasis Control Programme in West Africa

Programme de Lutte contre I'Onchocercose en Afrique de I'Ouest

JOINT PROGRAMME

COMMITTEE JPC . CCP

^{COMITE CONJOINT}

^DU

^PROGRAMME

Office of the

Chairman -

Bureau du Prdsident

I

JOINT PROGRAMME COMMITTEE Seventeenth session

Cotonou. 2-4 December ¹⁹⁹⁶

JPCI7.2

ORIGINAL

: FRENCH September 1996

Page

6 6 6 7 9 10 10 12

12

t2 l4

15 15

l6 t6

l8

18

t9

Provisional aeenda item 5

PROGRESS REPORT OF THE WORLD HEALTH ORGANIZATION FOR 1996 (1 September 1995 - 31 August 1996)

Table of contents

SUMMARY

VECTOR CONTROL Climatic conditions

Aircraft fleet and aerial operations Treated areas

lnsecticides and control strategy Hydrology and tel etransmission

Entomological surveillance and evaluation network Monitoring of the aquatic environment

IVERMECTIN

(MECTZAN@) DISTRIBUTION AND EPIDEMIOLOGICAL

ACTIVITIES . .

^.

Ivermectin treatment

Evaluation of the ivermectin delivery system Epidemiological evaluation

.

.

Evaluations in the Original

Area . . . .

.

Evaluations in the extension areas

Ophthalmological evaluations

3

BIOSTATISTICS

AND

INFORMATION SYSTEMS

. . .

^. 17

TRANSFER OF ACTIVITIES TO THE PARTICIPATING COUNTRIES

. .

^.

Training

Public awareness and population mobilization effort by OCP

Country-specific workshops for decentralized epidemiological surveillance of onchocerciasis and the installation

of

community-based ivermectin

treatment.

²⁰

I

JPCI7.2 Page 2

INTERDISCPLINARY RESEARCH Insecticides

Vector identification Parasite identifi cation

Special entomological studies Epidemiological

modelling . . . .

.

Diagnostic tools .

Macrofi

I

Chemotherapy Project

Potential macrofilaricidal compounds

.

^.

Possible resistance to ivermectin

. .

^.

Continuation of the Macrofil Project after 1997 -

ADMINISTRATION

AND

SUPPORT SERVICES Objectives, organization and functioning of services Administrative costs

Budget and Finance Personnel

Supply and services

Transport and

commu;i.;i";;

^.

PUBLIC RELATIONS, INFORMATION AND DOCUMENTATION

ACTIVMES

With the World Health Organization With the Participating Countries

. .

^. With the statutory bodies

With the donors

With the aerial spraying contractor With the scientific community

. . .

^.

With the general public

Public relations and documentation Internal meetings

FIGURES

AND

ANNEXES

Fig. 1

^VCU Plan of operations

for 1996

³⁵

Fig.2

Annual transmission potentids

(May

1995-April 1996) Stmuliwn damnosurn

complex species infected with Onchocerca

volvulus

36

Fig. 3

Annual transmission potentials

(May

1995-April 1996) Simuliwn damnosum

complex savanna species infected with Onchocerca volvulus

. .

³⁷

Fig. 4

Weekly trend

of

infective females of S.damnosurn and infective larvae

of

Onclucerca sp.38 Fig.

5

^Mode

of

ivermectin treatrnent

in

OCP (1995-1996)

. . .

³⁹

Fig.

6

Number of ^persons treated with ivermectin in

OCP

⁴⁰

Fig.

7

Ivermectin treatment coverage as per distribution mode in

OCP ^4l

I

20 20

2t

22 23 23 25 26 26 27 27 27 27 28 29 29

,o

30

30 30 31 32 32 32 32 33 33 34

I

I

I

JPCI7.2 Page 3

STJMMARY

a) In

1995, the rainy season was particularly abundant in the whole of the Programme area, leading

to

considerable swelling

of

the rivers

in

most

of

the basins under

larviciding. In

contrast to the previous year, the

dry

season was clearly marked, particularly

in

the south-eastern basins

of

the Programme.

b)

The aircraft fleet used during the period under consideration decreased

in

number

from

eight helicopters during the 1995 rainy season to two at the end of the 1996 dry season. As regards the 1996 rainy season, only seven larviciding helicopters are planned to be used but an eighth aircraft is considered in case larviciding is to resume in northern Sierra Leone.

c)

The aerial spraying contract between OCP and the Evergreen Helicopter Inc (EHD company wils renewed in January 1996 for a three-year period after winning an international invitation to bid. This is the seventh contract signed with an aircraft company since the beginning of the Programme.

d)

^During the period

from May

1995

to April

1996, there was

a

ITVo decrease

in

the number

of

flight hours and about 3% decrexe in insecticide consumption. This decrease was due mostly to the cessation

of

aerial larviciding on the tributaries of the White Volta (Kulparvn, Mole) and the Niger (Sota,

Alibori) at

the beginning

of

1995 and

the

compelled cessation

in March

1995

of

^aerial

larviciding

in

the basins

of

north-eastern Sierra Leone (Mongo, Kaba and Kolente) because

of

insecurity reasons.

e)

The insecticide rotation strategy, aimed at preventing blackfly resistance and keeping the effects

of

larviciding on the non-target aquatic fauna

to

a minimum, was the same as that

of

the previous years. The use of the insecticides took into account the usual restrictions related to their toxicity, their cost-effectiveness and the level of susceptibility of the blackflies to the different chemical insecticides, namely the organophosphorous group (temephos, phoxim and pyraclofos).

0 ^At

^{present, the OCP} hydrological monitoring network comprises

of

about 150 water-gauges including 79 equipped with hydrological beacons, being an increase of four units ^as compared to the previous

year. This

increase

is

due

to the

refurbishing

of

some beacons

in

Sierra Leone in preparation

for

resumption of larviciding in ttrat country when the security situation improves.

g) In

the period

from May

1995

to April

1996, ten catching points out

of

^{127 (8.6%)} monitored regularly showed Annual Transmission Potential above 100 infective larvae per person per

year. If

the transmission due to the savanna species of the S. datnnosurn complex alone were considered, only

five

catching

poins

(4.7Vo), including three on the tributaries of the Oti, had an ATP above 100.

h)

The cessation of larviciding on some rivers in the original area had repercussions on the structure

of

the programme resulting

in

the closure

of

Tamale (Ghana), Kandi @enin), and Bamako (MalD subsectors on 31 December

1995.

Another major event was the closure of the headquarters of the Western Zonein Bamako in June 1996. The Odienne aerial operations base situated at the ^gateway to the western extension and within the southern extension of C0te d'Ivoire henceforth caters for the Western Zone headquarters.

D

The environmental impact studies initiated in 1995 in the basins of the Sassandra in COte d'Ivoire, Pru in Ghana, Milo in Guinea, and Mongo in Sierra Leone showed some influence of human activities as a whole on the aquatic environment. The degree

of

importance of this influence depends on the localization of these activities in relation to the concerned watercourses. These studies confirmed the

I i

a

JPCI7.2 Page 4

importance

of

such activities

in

contributing

to the

understanding

of the

results

of the

aquatic environmental monitoring which has been established by the programme.

j) ln

199511996 the Planning, Evaluation and Transfer Unit (PET) coordinated ivermectin treatment by the national tqlms to 2.6 million people in more than 11,500 villages and hamlets using the various methods

of distribution.

The coverage in terms

of

percentage of people treated compared with the census population was

on the

average 74.9Vo

for

large-scale treatrnent

by the

mobile teams.

Distribution through community self-treatment was pursued, with varying degrees

of

success, with a coverage around 79.6%. No severe adverse reactions were recorded.

k)

Eight non-governmental organizations (NGOs) were involved in ivermectin distribution in six

of

the Participating Countries; community self-treatment was the main method used. Large-scale (mobile teams) and passive distributions were also used.

l)

Epidemiological evaluations were carried out in the Kankelaba basin in the Original Programme area

to help in

decision-making

on

the cessation

of larviciding.

Complementary results

will

be necessary

in

¹⁹⁹⁷ before a decision can be made on definite cessation

of

larviciding in this basin.

m)

In the extension areas under combined larviciding and ivermectin treatment, several villages were evaluated in order to determine the incidence

of

infection in the cohort of parasitologically negative individuals who had never received

ivermectin. In

the eight villages situated

in

the basin

of

the Comoe

in

COte

d'Ivoire,

and the five villages in the basins of the Oueme and Okpara in Benin, the incidence

of

infection was zero as compared

to

an average

of 25% if

there had

not

been any intervention.

n)

In the river basins of the Original Programme area where larviciding has stopped, epidemiological evaluations were carried out by the national teams in the context of the epidemiological surveillance activities with a view to detecting any possible recrudescence of infection. The results were good in most situations. In one village, Zoulo on the Bougouriba river in Burkina Faso, the observed 25.SVo

prevalence

of

infection confirmed the recrudescence of transmission in that

basin.

Further intensive evaluations undertaken have revealed prevalences ranging from 0,0vo to 53%.

o)

The ophthalmological and parasitological assessment of the medium and long-term effects of large- scale ivermectin treatment after seven years of annual treatment in the basins of the Niger,

Milo

and Niandan

in

Guinea showed satisfactory results. Significant improvements

in

lesions of the anterior segment

of

the eye and

of

the optic nerve were observed. The overall results

in

the population showed a beneficial effect

of

ivermectin treatment on the ocular disease.

p)

The integrated analysis of the results of the entomological and epidemiological evaluations was carried out within the Programme under the coordination of the Biostatistics and Information Systems

@IS) of the PET

unit.

This analysis is now used in epidemiological modelling more and

more.

In order to better prepare the nationals for epidemiological analysis, emphasis has been laid on training and the transfer

of

OCP's data to the Participating Countries. BIS has also continued

to

assist the other OCP units in the use of computer technology.

q)

The countries, through the coordination

of

the PET unit, have carried out awareness raising

of the

communities, epidemiological surveillance

and

treatment

of patiens with

ivermectin, and

mobilization

of

resources

for

the implementation

of

the residual

activities. In this

respect, the Ministries

of

Health of the Participating Countries have organized workshops

in

collaboration with OCP

in

order

to

develop action plans and budgets

for

the short, medium and long term on the

t

1 a

I

I

JPCI7.2 Page 5

installation

of

community-based

distribution of

ivermectin

and the

decentralization

of

^the

epidemiological surveillance of onchocerciasis. The activities are presented in document lPClT .6.

r)

During the period under review OCP has pursued

its

usual

training

activities and awarded 23 fellowships between August 1995 and July 1996, thereby increasing to 453 the number of nationals from OCP Participating Countries having benefitted from OCP fellowships between 1974 and July L996.

A

survey was conducted among the Ministries of Health of the Participating Countries on the utilization

of

fellowship candidates after their

training.

Out

of

the 437 OCP fellows surveyed in February 1996,

it

^was

found

that

22.7% work at

OCP

or in

national onchocerciasis control prograrnmes of the countries.

s) With six

chemical and one biological insecticides,

all fully

operational, the evaluation

of

the efficacy of new anti-blackfly larvicides ^is no longer a

priority.

As a result, research efforts are now focused

on the quality

control

of the

operational

lots

and

the

improvement

of the

existing formulations,

B.t. H-t4 in

particular, given

the

gain that

a

decrease, even

if minimal, in

the operational dosage would represent. The monitoring of blackfly susceptibility to the currently used insecticides was pursed with the usual rigour on all the rivers treated.

0

^The identification

of

female blackflies

of

the S. dannosurn complex through the heteroduplex analysis of the

DNA

has been operational since May 1995. Priority is currently given to the females originating

from the

forest/savanna transition zones where

the

possibilities

of

identification by morphological and morphometric techniques are limited because

of

the heterogeneity of the vector populations and of the over-lapping of the criteria used for certain differentiations.

u)

During the period under consideration, special entomological studies were undertaken in some

of

the Programme areas where onchocerciasis control

is

experiencing some

difficulties. They

are northern Sierra Leone, the lower Black Volta region, the Kulpawn/Mole and ^Oueme basins. These studies were aimed

at

^gaining

a

better knowledge

of

transmission conditions

in

order

to

take appropriate measures.

v)

High, single doses

of

ivermectin, while proving safe to administer, did not show any additional macrofilaricidal action over the standard (l50pg/kg) doses. However, results from the O.ochengi

I

cattle model show

that

administration

of

ivermectin

is

prophylactic.

Further clinical trids

on amocarzine,

for

both onchocerciasis and lymphatic filariasis, have been completed during the year, with no adverse results which prevent further development. Single intramuscular doses of UMF078 have shown macrofilaricidal activity inthe O.ochengi lcattle model, and its preclinical development continues. Studies

of

the mechanisms

of

ivermectin resistance

in

parasitic nematodes

of

veterinary importance are being continued,

with the aim of

generating

a

molecular probe able

to

^detect

ivermectin resistance in onchocerciasis

if it

should occur.

w)

The Administration and Support Services Unit has continued

to

support

all

the OCP units and prograrnme activities by managing in the most rational way possible and in the best interests

of

the Programme, the human, material, financial and informational resources

at its disposal.

Special emphasis has been laid on staff reduction both in the categories

of

professional and general service

staff.

The unit has also carried out the moving of the Bamako base in the context of the transfer

of

the zone headquarters to Odienne.

x)

The Programme has pursued its liaison, information and public relations activities and continued to keep the Donors, the Participating Countries, the countries not included in the Programme area, the scientific community and the public at large regularly informed about these activities.

JPCI7.2 Page 6

VECTOR CONTROL Climatic conditions

l.

^{The months}

of July,

August and September 1995 were particularly

wet in

the whole

of

the hydrological network of the Programme, causing considerable swelling of the rivers

in

most

of

the basins under larviciding, especially those

of

the Niger,

Milo,

Niandan, Tinkisso, Lake Volta, Oti, Mono and Oueme.

In

contrast to the previous year, the

dry

season was clearly marked

in

1996, especially in the basins of the south-east extension (Ghana, Togo, Benin) where larviciding was totally interrupted

from

18 March to

27

April because of poor water flow.

Aircraft

fleet and aerial operations

2.

The number of helicopters used under the contract during the period under consideration ranged between eight (from July to December 1995) and four

(April

1996). From ¹⁵

to27

April1996, only

two

helicopters were actually used due

to the

good entomological results

following very

low discharges

in the

whole Programme

area. For the

1996

rainy sqnon, only

seven larviciding helicopters are planned but the use

of

an eighth aircraft is considered in the event

of

resumption

of

larviciding in norttrern Sierra Leone.

3.

1995 was the last year

of

the

third

contract between OCP and the Evergreen Helicopters Inc.

(EHI) in

charge

of the

aerial spraying

of

anti-blackfly

lanicides.

Following

the

issuing

of

^an

international invitation to bid, the same company was selected

for

another three year contract which began in January 1996 and is due to end in December 1998. This is the seventh contract awarded

to

an aerial contractor since the beginning

of

the

Programme. In the

execution

of

the ^present contract, it was decided between EHI and OCP to keep two spare helicopters in the Programme area instead of one and have the possibility

of

calling

for

only four additional helicopters instead of five.

As in the

previous contract, OCP guarantees the company

that it will

use

a

minimum

of

four helicopters during the

dry

season and

six

in the rainy season. Some problems

of

aircraft and

pilot

availability have however been brought

up in

February 1996

at a

meeting held

in

Ouagadougou between OCP and the aerial contractor.

4. ^During

the period

of May

1995

to April

1996, the helicopters used 4850

flight

hours

for

larviciding (none

for

prospecting) as against 5882 during the same period

in

199411995,

viz

1032 hours less which represents a saving of about US$ 750 000

(table 1).

This decrease

of

l7 Vo in

flight

hours is mainly due to the cessation, at the beginning

of

1995,

of

aerial larviciding on the tributaries of the White

Volta

(Kulpawn, Mole) and the Niger (Sota,

Alibori)

and to the compelled ^cessation

in

March 1995,

for

security reasons,

of

aerial larviciding in the basins

of

the north-east

of

Sierra Leone (Mongo, Kaba and Kolente).

5.

^Compared

^to

the period

of May

L994lApril 1995

(Iable 2),

the Programme has reduced

is

larvicide cost by about US

$

¹⁰⁸ 000 ^(3Vo approximately). This difference is due

to

a decrease in the consumption

of

permethrin and pyraclofos, partially compensated

for by

an increase

in

the consumption of carbosulfan and etofenprox (Vectron), the latter having become fully operational since its definite acceptance by the Ecological Group in January 1995. Temephos, B.t- H-14 and phoxim were used in about the same quantities.

o'

?

JPCI7.2 Page 7 Treated areas @g.1)

6.

Vector control operations

in the

Original Programme area,

at the

beginning

of

1995, had definitely ^ceased on the Sota and

Alibori

(tributaries of the Niger in Benin), and on the Kulpawn and

the Mole

(tributaries

of the White Volta in Ghana).

Treatment operations, however, are still continuing on the Kankelaba (tributary

of

the Bagoe

in Mali)

and on the Dienkoa (tributary of the Black Volta in Burkina Faso as ground larviciding), on the Kara, Keran and

Mo

(tributaries of the Oti in Togo) ^and on the lower Black Volta in Ghana (downstream from

is

confluence with the Fako) including its tributaries the Tombe, Tain and Subin, as aerial larviciding.

7

.

As a result of the persistent insecurity, none of the basins of northern Sierra Leone were treated during the period under consideration. The Sewa and Bagbe rivers ^have not been treated

for

almost four years. Larviciding on the Rokel had also been suspended since

April

1994 and on the Kolente, Mongo and Kaba since March

1995.

Security conditions, however, seem to be returning to normal and the distribution

of

ivermectin which was resumed

in March

1996

in all of

these basins is scheduled to be followed by a resumption of larviciding very soon.

8.

^Since January 1996, ground larviciding on the Niger, near Bamako, and some

of

its tributaries Fie, Faya and Dylamba is being entirely carried out

by

the national team

of Mali, with

financial support and technical supervision from OCP.

9. In

the basins

of

the southern extension

in

COte

d'Ivoire,

the south-eastern extension and the western extension in Guinea, which have been under larviciding respectively since 1979, 1988 and 1989, there has been no change in the larviciding coverage during the period under consideration.

It

must be recalled that the tributaries of the Oti (Keran, Kara and Mo) are now considered part

of

the south-eastern extension because of the ^permanent infiltration, up

to

1988,

of

infective blackflies originating from adjacent basins situated fur0rer south.

a

JPCI7.2 Page 8

Table

I

Use of larviciding

flight

hours from May 1995 to

April

1996 and comparison

with

the previous period.

Table 2

Iarvicide

consumption

from May

1995

to April

1996

and

comparison

with

the previous period.

Months

Flight hours

Difference between 94/95

and 95196 May 94-April 95 May 95-April 96

May 355 322 -JJ

June 619 s38

-81

July 599 379

-

220

August 6r7 497

-

¹²⁰

September 557 345 - 212

October 409 246

-

163

November 477 576

+99

December 562 480

-82

January 476 472

-4

February 444 ss9

+

¹¹⁵

March 507 288 219

April

260 148

- ttz

Total 5 882

4

850

-1032

Larvicides Quantity ^used Difference between

94195 and95196

Cost May 94-April 95 May 95-April 96

US$

Temephos 042

3t4

040 432

-

1 882

(4%)

- _{26 23s}

B.t.

H-14 218 335 228 773

+ ^t0

^{438 (s%)}

+

48432

Phoxim 017 944 020 361

+ 2

417 (l3Vo)

+ 4t

137

Permethrin 028 995 015 155 -13 840 (48Vo)

-

142

4t4

Carbosulfan 013 991 019 165

+ 5

174 (37Vo)

+

107 723

Pyraclofos 047

t95

03s 0s3

- t2 t42

^(-26Vo)

-321

156

Etofenprox 009 176 016 825

-

^{7 @e (83%)}

+

184723

Total 377 950 375 764

- ²

^{186 (-t%o)}

-

107 790 (-3V")

a

tPCt7.2 Page 9 Insecticides and control strategy

10.

The insecticide rotation system, which is aimed at preventing possible blackfly resistance and keeping the effects

of

larviciding on the non-target aquatic fauna to a minimum, has been the same as in previous

years.

The insecticides have been used by taking into account the usual restrictions related to their toxicity, their cost-effectiveness and the blackfly susceptibility levels, particularly with regard to the organophosphorous (temephos, phoxim and pyraclofos).

11. ^As

is the case every year, the basins

of

the lower Bandama,

N'zi,

Comoe, Maratroue and lower Black Volta have been the subject of particular attention on account of the noted resistance to the organophosphorous. Temephos is still not used in these four basins, while pyraclofos and phoxim have been used sparingly,

with

phoxim totally excluded from use

in

the larviciding on the lower Bandama. This control strategy has had consequences on the consumption of the other insecticides, particularly that

of

etofenprox, the

only

non-organophosphorous insecticide that can be used at discharges between 15 and 70 m3/s.

I2. In the other

basins,

no

particular restriction

was

observed

during the period

under consideration,

with

the exception

of

the

Niger, in

the Bamako area, where the savanna blackflies developed resistance

to

pyraclofos

in 1995.

For that reason and despite the clear improvement

of

their susceptibility to temephos, permethrin, carbosulfan and etofenprox were used preferentially.

13.

^In accordance with the recommendations of the Ecological Group, permethrin ^and carbosulfan were not used at discharges below 70 ^m3/s and never

for

more than six consecutive cycles over the same river stretch. The Niger was the only exception, ^due to the very high discharges recorded over several weeks and the restrictions on the use of organophosphorous. Carbosulfan was practically not used on the Sankarani, the

Milo

and the Niandan so :rs to allow the continuation

of

the long-term impact shrdies of permethrin on the non-target aquatic fauna.

14.

During the period under consideration, ceftain operational

los

of

B.t.

H-14 (Vectobac), did not quite meet the terms of the specifications of the contract between OCP and the Abbon Company.

The value of the

CL,

at the time of delivery had then to be revised upward (135 mg/l/s instead

of

115 mg/l/s) at the cost of split up deliveries in order to reduce stocking time in the field (four months instead of

six).

The Abbott company is continuing research to determining the re:sons for the recent poor performance with a view to deliver to OCP in the shortest time possible a formulation that ^meets the terms of the contract.

15. ^In

1996, the total length

of

rivers likely to be treated from the air and from the ground

for

the purpose

of

preventing transmission

is

12,433

tiln.

This maximal larviciding coverage

is, of

course, theoretical

as it

includes northern Sierra

Leone. During the

week

of 30

October to 5 November 1995, period of

fall

in water level and therefore of high larval

productivity,9,l35

km

of

river were treated Qa% of the maximal coverage), mobilizing seven helicopters under contract.

The

week

of

¹²

to

18 June 1995, period

of rise in

water

level

and therefore

of high

larval productivity also saw a high larviciding coverage with 7,032 km

of

river

treated,viz.5T% of

the theoretical maximal larviciding coverage. Conversely, the week

of

¹⁵ to 20

April

1996, low-water period and therefore low larval productivity, saw the lowest larviciding coverage

with

1,630 km

of

river treated (13% of the maximal coverage) and the use of only two larviciding helicopters.

JPCI7.2 Page

l0

Hydrology and teletransmission

16. At

present, the hydrological monitoring network consists

of

150 water-gauges including 79 equipped with hydrological beacons,

i.e.

an increase

of

^four units compared to the previous ^year.

This

increase is due

to

ttre refurbishing

of

some beacons

in

Sierra Leone

in

the hope

of

resuming larviciding in the near

future.

This hydrological system, which is linked to a discharge forecasting software (PERLES) that relies on the teletransmitted data, makes it possible to improve considerably the efficacy of larviciding by providing hydrological data in real time and allows sometimes forecast of hydrological conditions of the rivers.

17

.

The utilization of all the beacons is made on the basis of a flat annual charge under a contract signed between OCP and the company in charge of teletransmission (Argos Company). The satellite reception stations are located at Odienne and Kara, ttre

two

aerial operations bases

for

which the information is indispensable. The coordination of the hydrological monitoring activities which was previouslybased at Odienne, has just been relocated in Ouagadougou, at the Prograrnme headquarters.

A third

station is due to be installed for that purpose.

It will

be operational on an equal basis with the other two, thereby allowing OCP to have at its disposal a source

of

supplemenury information

in

^case of a failure of the Odienne and Kara stations.

18.

^Two OCP hydrologists brigades (one at Odienne, one at Kara) and three national brigades (two

in

Guinea and one in Sierra Leone) carry out the day-to-day maintenance of the Programme's hydrological monitoring

network.

They have the capacity

to

diagnose any failure

in

the beacons, make the necessary repairs and redeploy them

if

^needed after performing

a

new gauging

of

the stations and readjusting the former hydrography

chart.

During the period under consideration, two training seminars were organized in the Programme area. One of ^{these was} more particularly aimed at the national hydrologiss in the context of their in-service

training.

The second, which was more specialized, made

it

possible

for

two OCP hydrologiss and three electronic technicians to receive training enabling them

to

repair 80%

of

the defective parts

of

the beacons and their accessories, thereby going beyond the simple day-to{ay maintenance performed before.

Entomological surveillance and evaluation network

19.

^At present, the entomological evaluation network in the treated zone comprises 127 catching points visited regularly, 76 of which are monitored every week and

5l

every

fortnight.

Catches can be organized on demand in occasional monitoring poins

for

the purpose

of

finding explanations or solutions to incidental entomological problems raised during the weekly briefings.

20.

^{On the} whole, the results of the entomological evaluation were satisfactory in all of the treated zone of the Programme. Transmission was negligible in the dry season (only one infective female was caught during the week

of

8

to

14

April

1996) but intense during the periods

of

high larval productivity and of increased man/vector contact (38 infective females caught during the week of 28 August to 3 September 1995).

2l

. ^In

all of the treated basins, transmission continued to be contained

.

However, some rivers have posed some problems. These include particularly rivers to the east of the Programme area in the forest/savanna transition zones (lower Comoe in C0te d'Ivoire, Oueme and Okpara in Benin), the Pru

river in

Ghana and the tributaries

of

the

Oti in

Togo (Keran, Kara and

Mo). Yet,

a significant decrease of Annual Transmission Potential (ATP) was observed in these basins even though the values remained above 100 infective larvae per person per year.

tPCt7.2 Page 11

22.

^{As in every year at the same} period (February, March and

April),

high densities of blackflies were caught to ttre west of the Programme area on the Sankarani, the Marahoue and the Sassandra.

These populations, however, were lightly infected, as they had probably been brought in the ^area by the harmattan winds blowing from the regions further north freed from onchocerciasis.

23.

^{Since the} installation

of

the Bouake molecular biology laboratory,

all

infective larvae

of

onchocerca collected during the dissections have been identified through specific DNA probes. Witlt this method, ^parasites of animal origin can be separated from the human onchocerca which, in turn, can be differentiated further into"forest" ^and "savanna" strains. The DNA-technique, combined with the morphological identification of vectors, ^makes it possible to establish two types of

ATP.

The first type shows the transmission of human onchocerciasis

by

all the species of the Simulium datnnosum

complex.

The second type shows the transmission of human onchocerciasis

by

savanna blackflies alone.

24. A third

type

of ATP,

proposed during the previous year, concerned ransmission

of

the

"savanna" strain of the parasite alone, regardless of the identity of the

blackfly.

However, this last

type will not

be recognized

in

the immediate

future

as there seems

to exist,

especially

in

the forest/savanna transition zones (northern Sierra Leone, southern COte d'Ivoire, Oueme basin, etc...), intermediate pathogenicity levels which are difficult to identifiy by the "savanna"

or

"forqst" probes of the parasite.

25.

^{On the basis of} this distinction and taking into ^account the same catching points as those

of

the previous period,

only

10 catching points out

of

127 visited regularly showed ATPs

of

human onchocerciasis above 100 infective larvae per person per year (figure

2). Five of

the

poins

are located in the border zones of the Programme area,

four

in the basin of the Oueme and one on the lower Comoe.

If

only transmission by the savanna species of the S. damnosutn complex (figure 3) is considered, only five points out

of

127 show ATPs above ^100, three located on the tributaries

of

the Oti

(Iitira,

Tapounde and Bagan), one on the Pru (Asubende) and one in the basin of the Oueme Q(aboua).

26.

^{Figure 4 shows the} evolution of the average number of infective blackflies (5. dannosurn s.l.) and

of

infective larvae of the parasite (without species distinction) in the 146 catching points visited regularly since

1990.

The downward trend was confirmed again this year, especially as regards, infective larvae, but a stationary situation seems to be developing

with

regard

to

infective females during the ^past three years.

27. ^{Even though} it ^is

operational,

the

technique

of DNA

mitochondrial (heteroduplex) identification

of

the adult species

of

the S. damnosurz complex was applied this year mainly for experimental purposes with a view to its validation against the cytotaxonomy method, the reference

technique.

Research

is

currently under way

to

adapt

this

technique

of the

identification

of

the parasite,

in

particular

of

the infective larvae

for

which

a finer

identification would be desirable

(cf.76).

28.

The definite cessation

of

larviciding on certain rivers of the original area had repercussions on the structure of the Programme which saw the closure, at the end

of

^1995, of the Tamale (Ghana), Kandi @enin) ^{and Bamako} (MalD sub-sectors. The closure of this last sector enabled the reactivation

of the

Operational Base and

the

national team

of Mali to

take

over

^ground

larviciding

and entomoloErical evaluation. Another major event was the closure, on 30 June 1996,

of

the zonal headquarters at Bamako which was no longer central

in

relation to ttre treated areas. The Odienne aerial operations base, located at the gateway

to

the western extension and

within

the southern extension

of

COte d'Ivoire henceforth caters

for

western zone headquarters.

tPC17.2 Page 12

Monitoring of

the aquatic environment

29.

^Since the expansion of the mandate of the Ecological Group, emphasis has been laid on the aquatic environment monitoring activities and the evaluation

of

the impact

of

factors other than insecticides on the aquatic environment. However, the study

of

the long-term impact

of

the less selective larvicides (permethrin, carbosulfan and pyraclofos)

on the

non-target aquatic fauna is

continuing.

The national hydrobiology tquns which have been initiated

in

environmental impact studies, continue

to

take an active and primordial part

in

the implementation

of this

monitoring prograrnme. The coordination of these activities as well as of some special evaluations is ensured by the Hydrobiological Monitoring Sub-unit (HMS) of the Programme.

30.

The environmental impact studies initiated

in

1995

in

the basins

of

the Sassandra

in

^C0te d'Ivoire, of the Pru in Ghana, of the

Milo

in Guinea and of the Mongo in Sierra Leone indicate some influence of human activities as a whole on the aquatic environment. The degree

of

importance

of

this influence depends on these activities location in relation to the watercourse. On the

Milo

^and the Pru for instance, an absence of activities likely to influence the biological quality of the watercourses is noted. Disturbances in the structure of the invertebrate populations were observed in the

Milo

but

fish

stocks have increased compared

to

those

of the

previous years

in the two

watercourses.

However, in the Sassandra and the Mongo, human activities ^have been on the rise causing significant disturbances both

in

the

fish

and benthic invertebrate populations. These studies confirmed the importance

of

such activities

in

contributing

to

the understanding

of the

results

of the

aquatic environmental monitoring which has been established by the Programme. They are being consolidated

in

order

to

ensure a better appreciation

of the

impact

of

such activities

in

the current biological situation of these watercourses.

31.

^The routine monitoring shows a decrease in the densities of the non target insects and some modifications

of their

population strucnrres

in the form of

rareness

of

some taxa such as the Tricorythidae. These modifications do not seem to be prejudicial to the energetic balance between the different guilds and are therefore considered to be acceptable. With regard to the fish fauna, a

relatively stable abundance has continued to be observed in most of the watercourses treated except in COte d'Ivoire where catches have been decreasing gradually in even those rivers no longer under treatment. The situation

of

"fleshy" fishes is fluctuating around a relatively stable average;

thxe

fluctuations are to be linked to the hydrological conditions and to reproduction phenomena. In respect

to

species diversity, the almost total disappearance

of

Petrocephalus bovei

from

^catches

in

COte

d'Ivoire and the decrease in the abundance

of

Chrysichtys auratus in Guinea are to be noted. Special attention is currently paid to these species.

32.

This year, the hydrobiologists have started the preparation of two consolidated reports ^(one on ichthyologic and the other on invertebrate faunas) over the 20 years of monitoring of the aquatic environment subjected

to

anti-blackfly

larviciding.

Emphasis

will

be laid on the evaluation

of

the possible impact of the alternated use of these larvicides.

IVERMECTIN (MECTIZAN) DISTRIBI.ITION

AND

EPIDEMIOLOGICAL ACTIVITIES

Ivermectin treatment

33.

^The Planning, Evaluation and Transfer Unit coordinated the distribution of ivermectin carried out by the nationd

teams.

These

were

supported financially and logistically by the Programme.

Eight non-govemmental organizations (NGO) supported the treatment in Guinea,

Mali,

Senegal and Sierra Leone, in the form of funds and other logistics for a community-based delivery. The treatment

tPCr7.2 Page 13 was carried out through large-scale-scale distribution

in

the areas previously ^mapped out to be areas

of high risk of onchocercal eye disease and/or blindness,

i.e.,

areas that previously had CMFL1

of l0

mf/s or more. Treatment was also extended to all the endemic areas The areas concerned are in the southern extension: Benin, Cdte

d'Ivoire,

^{Ghana and} Togo; and the southern part of the western extension, Guinea and Sierra Leone.

It

is recdled that in the northern part of the western extension,

in

the area north

of

the Tinkisso

river

basin, there is no larviciding and ivermectin use is the only means of control. Large-scale ivermectin treatment was continued in the zones where the CMFL was at or above 5 mf/s. Large scale distribution was enlarged to cover other villages in the endemic areas after having satisfied the set criteria above,

Fig. 5.

Ivermectin treatment was suspended as from January 1994

in

Sierra Leone due to the uncertain security situation in the country, however, since Marcir this year treatment ^has been restafted in a limited area in the north of the country.

34.

Large-scale ivermectin treatment was carried out in certain parts of the Original Programme area. These were well defined and specific ^{areas where} the entomo-epidemiological resuls had not been

fully

satisfactory, such as

in

the Kulpawn/Sissili,

Mole

and Black Volta basins

in

Ghana, Dienkoa basin

in

Burkina Faso, the previously reinvaded zones

-

Bago6, Kankelaba

(Mali),

Sota, Koumoungou @enin), Kara-Keran-M6

(togo)

and the north of the extension zones in C6te d'Ivoire.

Large-scale ivermectin treatment has been started in a circumscribed area in the Bougouriba basin in Burkina Faso as a measure to stem the recrudescence which has occurred in the ^area.

35. ^All

the ivermectin distribution in the field ^was carried out entirely by the national teams using mostly the large scale (mobile)

method.

This accounted

for

around 63%

of all

treatments. The community-based treatment which is also large scale distribution but operationally different in ^terms

of

logistics, financing and the personnel involved, accounted

for

around 33Vo

of the

ivermectin distribution

in

contrast

to

the

26 %

obtained the previous year. About 4%

of

the treatment ^was through other modes of distribution, ^as

for

example passive treatment.

36.

Community-based treatment already

firmly

established

in

Guinea

and Mali'was

^also

undertaken in varying patterns and to several degrees in several

ofthe

countries including Senegal, Benin, Ghana and Sierra Leone. In this form of distribution, literate members of the village, selected by the villagers themselves, carry out the distribution under the supervision of the health staff from the nearest health centre.

37.

^{The use of} other volunteer services

for

ivermectin delivery was extended in Ghana to other basins hi0rerto under the mobile form

of

treatment .These volunteers took part

in

the distribution exercise at the same time with the national team. This ^has helped to reduce the workload on, and the time spent in the field by the treatment teams. The communities' acceptability of the community-based treatment method of distribution ^has been excellent. ^So far, drop-outs of the village distributors has been insignificant.

38.

^In the year under review, eight NGOs ^were involved in the ivermectin distribution in the OCP area at varying degrees of participation. The NGOs worked in concert with the national teams in well demarcated and specific river basins, making

full

use

of

the epidemiological mapping prepared by OCP and in collaboration with the National Onchocerciasis Coordinators. Their main support was in logistics and funds

for

the community-based ivermectin distribution. The number

of

people treated with the support of/or by the non-govemmental organizations was 868,000 which accounted for about 33Vo of the treatmens in the OCP.

t CMFL: Community Microfilarial load

ORGANIZATION COUNTRY MODE OF TREATMENT

BMRC xSierra Leone Large-scale (mobile) treatment

CBM (Lunsar) *Sierra Leone Large-scale (mobile) treatment

CFAR Mali Community based treatment

OPC Guinea,

Mali,

Senegal Community based treatment

PhilAfricaine Suisse Guinea passive

Save the children Sight Savers

Mdi

*Sierra Leone, Mali Ghana, Guinea

Community based treatment Community based treatment

Trop. Inst. Germany Togo passive

JPCL7.2 Page L4

Table

3.

^{NGOs involved}

ⁱⁿ

ivermectin

distribution in

the OCP aru,1995196

x Treatment in this area

was

suspended in early 1994 due to security problems in the ^area.

BMRC: British Medical Research Council

CBM :

Christoffel Blindenmission

OPC

:

Organisation pour la prevention de la ^c6cit6 CFAR: Centre de formation d'animatrices rurales.

39.

^{From September 1995} through

July

1996, more than

2.6

million people were treated with ivermectin through the various modes

of

distribution

in over

11500 villages and hamlets (Fig.6).

Most of these villages are in the extension areas. The average coverage i.e. number of people treated divided by the total census population, through large-scale distribution by the national onchocerciasis tqrms

wx 74.9%. The

distribution through

the

community-based treatment ensured

a

higher coverage

of

^79.6Vo

(Fig.7).

This high coverage from the community-based treatment is ^due to the fact that treatment was available

for

a relatively longer period at a time

in

the villages than

it

^is

through the mobile team. Thus, individuals who might have been excluded from treatment for some reason, and become eligible later, receive their treatment without having to wait until the following year.

40.

Monitoring

for

severe adverse reactions was carried out as required, after each treatment especially

in

areas

or

for groups

of

individuals receiving ivermectin

for

the first time, by the teams

carrying

out

ivermectin

distribution.

Each team undertaking large-scale distribution has

a

drug monitoring kit to undertake treatment of any severe adverse reactions, should this be necessary. The system

of

several treatment teams

being

supervised

by

a medical off,rcer during the distribution period was maintained.

In

the case

of

community-based treatment, the occurrence

of

any severe adverse reaction would be reported

to

the distributor who would then report to the nearest health centre. No severe reactions were recorded during this treatment season.

Evaluation

of

the ivermectin delivery system.

4l

.

Evaluation of the ivermectin d istribution system in Benin, COte d'Ivoire, Ghana and Togo was carried out in the year under review. This was a follow-up to a similar exercise which was undertaken

in

Guinea,

Mali

and Senegal last year.

In

all a sample

of

130 villages were selected at random and used

for

the evaluation, employing a structured questionnaire, examination

of

records and focus group discussions.

a

JPCI7.2 Page 15

42.

^In general the population treatment coverage was good, at an average of

67.2%.

This ^was higher than the optimum treatment coverage, 65%,

u

^a proportion of the total population which ^has been established

for

adequate morbidity

control.

The population coverage in Togo was the lowest at 6l.8Vo . About 30% of those questioned admitted to have received treatment during each of the five to six cycles of distribution, while 26.1% claimed never to have received treatment. Of those that had

'never

been'

treated, 54% had, been absent during treatment periods and only 2.6Vo had actually refused treatment. In general the acceptability

for

ivermectin treatment was excellent.

Epidemiological evaluation

43.

Epidemiological evaluations were carried

out in the

OCP

with the

help

of the

national onchocerciasis teams and as before with the following objectives:

to help decide on stopping larviciding;

to assess the impact of the control activities through the ^measure

of

incidence in the western and southern extension ^areas and other specific areas in the original area which are subjected to both ivermectin distribution ^and larviciding.

Evaluations in the Original Area

44. In the Original

Programme area, epidemiological evaluations were carried

out in

the Kankelaba basin in

Mali

in January this ^{year as a} first step towards obtaining results to help with the decision as to whether larviciding could be stopped in the

basin.

Given that ivermectin treatment ^is also carried out

in

the area, the results

of

^a subsequent evaluation planned

for

1997, at least two years after the last ivermectin treatment in the ^area

will

be needed to be able to take the decision

of

whether

or

not larviciding could be stopped in the basin.

45. For

this evaluation three indicator villages,

i.e.,

first-line villages which have had several evaluations in the past, in addition to three newly identified villages were ^examined in January 1996.

The classical parasitological method of skin snipping was ^used to assess the prevalence

of

infection, the intensity of infection and the presence of any new infections. For this particular situation in the Kankelaba basin new infections are defined as infections in children of five ^years

of

^age or less and do not receive ivermectin treatment. The prevalence

of

infection at

this

preliminary stage from the six villages evaluated ranged from 0.0% to

8.1%.

^No new infections were observed.

M. In the river

basins

of the

Original Programme area

in which

larviciding has stopped, epidemiological evaluations

:re

carried out by the national teams in the context of the surveillance

of

the sentinel villages so zls to detect any possible recrudescence of infection. The results which were excellent

in

most of the situations were recorded in document JPC

17.6.

However, in one village, Zoulo on the Bougouriba

in

Burkina Faso, the observed prevalence

of

infection

of

25.5Vo made

it

possible

to

confirm

a

resumption

of

transmission

of

the infection

in

this

basin.

Complementary intensive epidemiological evaluations which were carried out showed prevalence rates ranged from O.lVo

to 53Vo. In

accordance

with

the ONCHOSIM model predictions, a biannual

distributionof

ivermectin was instituted and began

in

June 1996

in

order to bring this resumption

of

transmission in the area under control. ^(See para. 90 and 91)

JPCI7.2 Page 16

Evaluations in the extension areas

47.

Evaluations were undertaken in eight villages in the Comoe basins

(

COte

d'Ivoire)

and the Okpara and Ou6md basin @enin)

in

the south-eastern extension.

The

parasitologically negative individuals (individuals shown

to be

negative

on two

consecutive occasions)

in

these villages constituted a cohort of individuals for follow-up in respect to incidence of infection. Such individuals

did

and

will

not receive ivermectin treatment

in

the course

of

the annual ivermectin distribution

campaigns.

However, any such individuals who are subsequently found

to

be parasitologically positive

will

be placed on ivermectin treatment; the so treated individuals

will

be removed from the cohort being followed

up.

The cohorts include both aduls and children.

48.

^In the Comoe basin, the prevalence

of

infection ranged

from

5.8%

to 50.6%.

Four of the villages evaluated recorded no new infections in the time between the evaluation carried out three years ago and the present evaluation.

In

the other four villages infection were recorded

in all

age groups.

In

one

of

these villages, 12 positive cases were recorded

in

children

of five

years old or below out

of

the 42 examined, i.e.28.6Vo compared to about 30% expected cases

if

there had been no intervention. In the five villages evaluated in the Oueme/Okpara basin, the prevalences of infection ranged from 5.3Vo

to

31.5% as compared to prevalences above 50% observed before the beginning of the interventions.

49.

Evaluations were carried out in the six villages in the Koulountou-Koliba basins in Guinea and

five

villages

in

the

Rio

Geba basin

in

Guinea Bissau both

in

the northern

part of the

western extension area, where ivermectin treatment ^is the only means of

control.

Treatment has been carried

for at

least

five

years

in

these

basins. The

emphasis

in this

evaluation

was to

assess the parasitological

profile

(incidence

of

infection)

of

children

of five

years

old or below.

These are children excluded from ivermectin treatment. The prevalence

of

infection in the Koulountou-Koliba and the Rio Geba basins ranged ftom 8% to 45 % and 0.0% to 3.27o respectively.

In

comparison, the pretreatment prevalence

for

the Koulountou-Koliba basin was over 5O%

in

all the villages while that

for

the Rio Geba basin ranged from 16% to

23.5%.

In both basins none of the children

of

or below five years old were found to be infected. Furthermore it was observed that only seven out

of

the over 774 individuals examined in the five villages of Rio Geba were found to be positive.

50. In

northern Sierra Leone, epidemiological evaluations were undertaken at the beginning

of

1996 as soon as security was restored

in

23 villages situated

in

the basins

of

the Kaba, Mongo, Mabole, Seli and Bagbe.

In

spite of the suspension of operations

for

two years, a stagnation of the crude prevalences

of

infection ranging ftom 7% to 73% was observed during this evaluation. The rate of participation by the population in the course of these evaluations was excellent, ranging from 59% to 94%.

Ophthalmological evaluations

51.

Ophthalmological evaluations were carried out in four follow-up villages in the

Milo,

Niger and Niandan basins

in

Guinea in the western

extension.

These evaluations were being carried out

after

seven cycles (seven years)

of

ivermectin treatment

given

once annually combined with

larviciding.

The present results were comp:red

to

those obtained

at

the

five

years post annual ivermectin treatment, in order to determine the medium-term evolution

of

ocular onchocerciasis.

52. ^The

results showed significant improvement over the

five

year period evaluation

in

the anterior segment

of the

eye

with

respect

to iridocyclitis.

There was

no

appreciable change in sclerosing keratitis. With respect to the posterior segment lesions, there was significant improvement

JPCI7.2 Page 17

in lesions of the optic nerve. The microfilarial load in the anterior chamber of the eye had reduced significantly

with

the present mean

of

0.03

mf

(maximum 7mf).The overall

results

indicated a

progressive beneficial effect

on the

eye

from the

ivermectin treatment.

The level of

^ocular

microfilariae

is now

at such

low

levels as not

to

induce any further development

of

serious eye disease.

BIOSTATISTICS AND

INFORMATION

SYSTEMS

53.

The Biostatistics and Information Systems subunit (BIS)

of

the PET

Unit

has continued to c:ury out the processing of the entomological and epidemiological evaluation data, with emphasis on supervision of the data entry and validation by the staff of the technical units of the Programme. The subunit has also continued to play a major role in computer assistance within the Programme. This assistance concerns training, management of the different data banks and their backup, and the routine maintenance of the various computer equipment installed in OCP.

54.

^The data banks for the administration have been completely reviewed during the period under consideration

in

order

to

improve the management

of

staff, finance, services and

supplies.

To standardize these different data banks

in

order

to

make

their

users more independent

in

their utilization, an updating of the prograrnmes and training of the users was carried

out.

The effective use

of

the programmes

by the

concerned

staff

has made

it

possible

to iron out

the diff,rculties encountered as the prograrnmes were being used.

55.

^{The use} of ^the SEPT-ONCHO software package @pidemiological Surveillance ^and Treatment

of

Onchocerciasis)

for

the transfer

of

OCP's data to the Participating Countries has continued to be the subject of training of the nationals. This computer programme and the epidemiological data once transferred to the countries

will

make

it

possible

for

the national epidemiologiss to exchange later with OCP the results obtained and to ^make routine analysis of data collected after each evaluation by comparing them

with

already existing

data. To

carry out this transfer correctly, the checking and general update of the epidemiological data bank remains

still

^{a priority} at BIS.

56.

The intensive use of the Geographical Information System (GIS) has facilitated the analysis of the entomological and epidemiological data. The computer'ud mapping component of the system has allowed the Programme's cartographer to ^{produce maps} which can easily be updated. The Map-

Info

software which has been used

for

nearly two years have allowed OCP

to

make considerable progress in the use of the

GIS.

Base maps of the countries in Africa have been ordered and received.

This allows a visualization of the data in the OCP area as a whole, and also in detail at the country

level.

Attempts have been made this year in the basins of the Oti in Togo and of the Bougouriba in Burkina Faso

to

use

the

system

of

automatic determination

of the

coordinates

in the field

to supplement our data banks on ivermectin

distribution.

This management and analysis

tool will

be introduced this year to the national teams for whom training sessions are planned towards the end

of

1996. In order to better utilize the resources of the system, collaboration with other institutions

will

be established to complement the data bank on villages located by their coordinates (longitude-latitude) in each country.

57.

^{Routine analyses involving} ophthalmological data, those

of

^the epidemiological sildies on ivermectin and those collected during the study on new diagnostic tools were made. A protocol has been developed and applied in the Kankelaba basin in order to better appreciate the epidemiologicd uends observed

in

a basin under both larviciding and ivermectin

distribution.

Data collected in the villages as part of the ophthalmological monitoring in the

origind

area where vector control has been